When the International Astronomical Union demoted Pluto from planet to dwarf planet in 2006, more than a handful of Americans were upset, or even outraged. But Neil deGrasse Tyson ’80, astrophysicist and director of the Hayden Planetarium at the American Museum of Natural History in New York City, wasn’t surprised at all—in fact, he had been arguing for Pluto’s demotion for years.

Tyson is perhaps one of the most visible American scientists of the past 20 years. His charisma and natural eloquence make him a popular guest on television shows such as “The Colbert Report” and “Late Night with Conan O’ Brien,” as well as the PBS program “NOVA scienceNOW.”

As an undergraduate living in Currier House and concentrating in Physics in the late 1970s, Tyson’s love of astronomy was infectious, and he wasn’t shy about sharing his passion with friends. Salim Washington ’93, who later took time off from Harvard, was roommates with Tyson in Weld during their freshman year and remembers Tyson’s intensity and focus.

“A lot of people came to college figuring out what they wanted to do, but not Neil. He had found his passion already,” says Washington.

Tyson was on the wrestling team and lettered in his senior year. He also spent a lot of time in the Harvard Observatory and sometimes invited others along. “Once, he took an ex-girlfriend of mine up to the observatory for a date,” says Washington.

Washington remembers that Tyson had already cultivated a talent for explaining difficult astrophysical concepts using layman’s terms. “He didn’t use any technical jargon—he just spoke in English,” Washington comments.

In August 2011, it was announced that Tyson would host a sequel to Carl Sagan’s television series “Cosmos: A Personal Voyage.” Sagan, another popularizer of science and mentor of Tyson, was occasionally criticized for oversimplifying scientific concepts, and it remains to be seen whether Tyson will suffer the same sorts of troubles now that he has assumed such a public persona.

“In terms of anybody who gets that much attention in the limelight, that kind of exposure automatically accrues some jealousy,” says Owen J. Gingerich, Professor Emeritus of Astronomy and History of Science.

The sequel to “Cosmos” won’t air until 2013, but for now it appears that Tyson’s star will only continue to rise.